Friction-assisted magnetic holding of an ingestible capsule for esophageal pH and impedance monitoring.

24-hour catheter-based ambulatory pH and impedance monitoring is an essential tool for diagnosing esophageal disorders. However, catheter-based monitoring systems are uncomfortable and interfere with normal activities of the patient. To overcome these disadvantages, different wireless monitoring systems have been proposed. However, efficient ways to position and hold wireless capsules are lacking. Currently there is a need to develop safe and reliable methods to hold an esophageal wireless monitoring system in position for 24 hours. Friction-assisted magnetic holding is proposed as an alternative to conventional holding techniques. Permanent magnet and electromagnet designs with the required characteristics to achieve this task were computer-designed and simulated. The size and power requirements of the magnets were considered. Simulation results were verified using laboratory experiments. Permanent neodymium magnets offered the best performance for the intended application. The obtained results show the feasibility of friction-assisted magnetic holding for esophageal monitoring. Improvements to the thread design, friction enhancing pins, magnetic shielding and encapsulation methods are necessary for in vivo testing.